During the past year we have completed three studies: 1) Using the criterion of linear or non-linear spatial summation over their receptive fields, the concentric cells in rabbit lateral geniculate nucleus were classified into non-lapping X or Y groups. 2) Using both light and electromicroscopic materials we have tried but failed to detect any cytoplasmic laminated bodies in rabbit lateral geniculate body. 3) The developmental changes of callosal connections of striate cortex in neonatal rabbits were studied with Nauta degeneration, horseradish peroxidase and autoradiograhic methods. The results show that in addition to the known connections at the V1 and V2 border, there were also sparse connections from the monocular region in young animals which disappeared later. Current studies include a program of fetal surgery in pregnant rabbits. A study of pre-natal monocular encleation on axonal sprouting of the remaining eye was initiated. Related to the above is a study on the time course of retinofugal fiber development in prenatal rabbits. Two studies using adult rabbit are in progress: 1) Using intraocular injection of H ion proline and H ion fucose to trace the organization of afferent visual system; 2) using the criterion of linear or non-linear spatial summation over the receptive field to classify striate cortical cells into X or Y groups. Finally, we are continuing a study on the effect of long-term monocular deprivation on rabbit striate cortical cells.